Supramolecular chemistry of [{M(CO)₃(μ₃-OH)}₄] (M = Mn or Re): A modular approach to crystal engineering of superdiamondoid networks

The compounds [{M(CO)₃(μ₃-OH)}₄] (M = Mn 1 or Re 2), which are cubane-like molecules possessing T_d symmetry with four strong hydrogen-bond donor moieties rigidly directed towards the vertices of a tetrahedron, cocrystallized with 2 equivalents of a series of linear difunctional hydrogen-bond acceptor molecules or 'spacers' to afford 14 three-dimensional superdiamondoid networks with varying, but predictable, extents of interpenetration according to X-ray crystallography. The extent can be rationalized on the basis of the volume and length of the spacer molecule: benzene, toluene, p-xylene, p-fluorotoluene, naphthalene, 1-methylnaphthalene (all via π-hydrogen bonds), N,N,N′,N′-tetramethylethane-1,2-diamine (tmen), 1,2-bis(diphenylphosphoryl)ethane (dppoe) and 1,4-diamino-benzene (dab) afford two-fold networks; 1,2-diaminoethane (en) and 2-chloropyrazine (cpyz) afford three-fold networks; 4,4′-bipyridyl (bipy) and 4,4′-bipiperidine (bipip) afford four-fold networks. The adducts 1·2dppoe, 2·2dab, 1·2bipy, 2·2bipy and 1·2bipip crystallize with enough space in the crystal lattice to enclathrate one, four, two, two and two acetonitrile molecules per molecule of cubane, respectively. All fourteen networks crystallize in space groups that reflect at least some of the symmetry inherently present in 1 and 2.